About a week ago I noticed my engine was starting to have a rougher idle than normal. A couple days later on the way home my check engine light started coming on whenever I coasted or hit the brakes with the car in gear between 2000 and 1500 rpm but as soon as i gave it any gas it would go right back off. It doesnt come on every time I decelerate or coast its more like every 3rd or 4th time. The idle has gotten worse over the past few days and now it will surge between 700 and 900 rpm after a cold start and idles really low like around 550 to 600 whenever the a/c is on. The only thing I have done to the car in the past few weeks was clean the k&n filter. I thought some of the oil may have gotten on the mass air sensor but i cleaned it with brake parts cleaner and it didnt help. Any ideas???? Also, will I be able to pull any codes since it is not a constant check engine light?